DE 10 2004 051 332 A1 discloses a generic actuating device. In the known solution, the pole tube on its one free end which projects out of the housing of the actuating device is provided with a flanged edge against which the armature can be supported in its one end-side travel position. The flanged edge leaves a center opening exposed into which a pressure equalization channel of the armature discharges which on its opposite side can be supported on the pole core in whose direction the pressure equalization channel discharges on its other side. For this purpose, a loose bearing point is formed by the coil body and delimited by the housing parts for the free end edge of the pole tube, which edge is directed to the outside.
On the opposite end, the pole tube has a flanged edge of less curvature which is directed in the opposite direction, and with which it is fixed in position between the coil body and the pole core both axially and radially in a fixed bearing point. As a result of the deflections toward the free edges of the pole tube, which is designed as a receiving sleeve for the armature and which is longitudinally displaceable, the pole tube is able to produce a certain longitudinal tolerance equalization in order to form a fitted mounting for parts of the actuating device. As a result of the defined clamping site of the receiving sleeve as the pole tube at the fixed bearing point between the pole core and the coil body, these tolerance equalization possibilities are limited. In order to seal the interior of the actuating device relative to the exterior, on the inner periphery of the receiving sleeve as the pole tube there is a sealing system, preferably in the form of an elastomer gasket which, mounted in the outer groove of the pole core, ensures sealing between the pole core and the pole tube. If the elastomer gasket has not been correctly installed or it was forgotten in installation, the sealing site can fail and the interior of the actuating device is no longer sealed media-tight relative to the exterior. This failure case can also occur when the sealing system is worn and therefore has become unusable due to long-term use.
To remedy the defect of the limited tolerance equalization possibility, DE 10 2005 061 184 A1 for a likewise generic actuating device has proposed forming the flanged edge of the pole tube as a closed bottom part of a receiving sleeve which, supported by the pole core, is in contact with the latter. The bottom part of the pole tube is able to fit into the pole core such that it maintains its location, even if the armature for actuating a valve which can be connected to the actuating device moves back and forth and, in doing so, presses especially on the bottom part or is lifted off it by pulling itself. Since the flanged edge no longer borders an annular passage site, as shown above, but rather is closed, in this case, use for high pressures is possible since, in addition to pressure tightness, a stiff, loadable pole tube system is formed.
By the defined contact of the bottom part of the pole tube with the pole core, a type of fixing is achieved which enables tolerance equalization elsewhere on the pole tube in a widely drawn region. At the same time, the pole tube on its free end discharges into a bead-shaped flange which is supported on the housing of the actuating device. The bead part of the flange is designed as a round bead. This design makes it possible to position the free end region of the bead-shaped flange between the housing of the actuating device and housing parts of the adjoining valve body by clamping. As a result of the elastically resilient bead body, a type of articulation is implemented along which, especially in the axial direction, the pole tube with its installation length can be fitted within the coil body and the pole core. Between the elastically resilient bead body and the connected valve housing of the valve in turn there is an elastomer gasket which is designed to ensure a media-tight seal between the interior of the actuating device together with the valve relative to the exterior. This known sealing system can also lead to the above-described defects of the lack of media tightness.